MONTPELIER — A group of Vermont lawmakers called for a national constitutional convention to reverse the effects of the U.S. Supreme Court’s Citizens United decision that allowed corporations greater influence in political campaigns.

Sen. Ginny Lyons, D-Chittenden, led a group of senators at a news conference Thursday calling for what would be the first constitutional convention since the one that convened in Philadelphia in 1787 to write the original Constitution.

“If we want real democratic reform we have to start it here in Vermont and urge our elected leaders in Washington to support free and fair elections, Lyons said. “It’s time for state leaders and local citizens to step up and take action to get our country back on track.”

While Lyons was joined by Sens. Robert Hartwell, Anthony Pollina, and others, the idea was not universally popular.

“Calling a constitutional convention potentially is one of the greatest threats to freedom that I can think of,” said Sen. Peter Galbraith, D-Windham.

He said limiting the agenda ahead of time would be impossible and such a convention could result in the United States being officially declared a Christian country, without abortion rights, freedom of speech, press or other rights, he said.

Others noted that Lyons and Hartwell were among the senators who earlier this session voted to help defeat a ban on corporate contributions to political campaigns in Vermont. Critics of the Citizens United decision, like Lyons, have complained that it opened the floodgates to corporate money in politics by equating corporations with people and money with speech.

The constitutional convention idea was raised on a busy day at the Statehouse as lawmakers rushed to finish their business for 2013 by what legislative leaders say they still hope will be a Saturday adjournment.

Other developments Thursday included:

Legislation to allow child care workers to unionize and negotiate with the state over subsidies for parents of children in their care and over working conditions failed in the Senate, after Lt. Gov. Phil Scott ruled it could not be added to a miscellaneous education bill, and supporters failed to muster the three-fourths majority needed to override that ruling.

The House debated much of the day before giving preliminary approval to a bill that would require labels on genetically modified food. The Senate lacks time to work on the measure this session, however, lawmakers said.

Supporters of marijuana decriminalization worked to resolve the differences between House and Senate versions. The stickiest among them was the Senate’s addition of language saying Vermont would shift from misdemeanor criminal penalties to traffic-ticket-like fines, not just for up to an ounce of marijuana but also up to five grams of hashish. The two contain the same active ingredient, with five grams of hashish being about equivalent to an ounce of pot.